I haven't really gotten high enough to know what is optimal yet. My second group is Brawler {my husband has an SK at 70 he'll swap in later}, Mystic, Templar, Illusionist, Conjuror, Troubador. We really like all the pets we get with that combination, +mez, charm, stuns, stifles and dazes all over the place. Seems to be working well for us so far.

I guess it would really depend on the rest of the group. My husband loves his SK for tanking. Since that's not the optimal defensive tank, I can see encounter-wide mez and single target mez as being a bigger bonus to us than extra damage, since SKs put out some nice damage on their own. Someone who prefers a Guardian or Paladin might prefer more damage since those are defensive tanks that don't dish out as much damage but can take a bigger beating.